Auger cleaners

ABSTRACT

A tool for removing debris from a helical blade of an auger or other screw-conveyor, the tool comprising a central shaft about which is helically arranged a plurality of radially projecting elements. In use, the tool is rotated as the auger is withdrawn from the ground, and the radially projecting elements pass between adjacent flights so as to remove locked-in soil.

CROSS REFERENCE TO RELATED APPLICATION

The present application is the national stage under 35 U.S.C. 371 ofPCT/GB98/03891, filed Dec. 23, 1998.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to tools for cleaning an auger, inparticular but not exclusively a continuous flight auger, as it is beingwithdrawn or after it has been withdrawn from the ground.

2. Prior Art

Augers are commonly used in civil engineering applications such aspiling, a particular example of this being Continuous Flight Auger (CFA)piling. A continuous flight auger comprises a generally cylindricalelongate body provided with a generally helical blade. Each 360° turn ofthe auger defines a flight of the blade, i.e. a flight is the spacebetween adjacent, longitudinally-spaced sections of the blade. In use,the auger is rotated into the ground to a predetermined depth at whichthe downward advance of the auger is halted. The auger may then bewithdrawn without further rotation, thereby shearing a “plug” of soildirectly from the ground so as to form a bore hole, or the auger may berotated before withdrawal so as to shear the soil on the flights fromthe soil which will eventually form the wall of the resultant bore hole.During withdrawal, concrete or grout may be pumped through the auger ordown a feed pipe under positive pressure so as to form a cast-in-situpile.

Upon withdrawal, the flights of the auger are generally loaded withsoil, and there is a danger that some of this soil will become lockedbetween adjacent flights instead of falling out cleanly as the augeremerges above ground level. As the auger continues to be withdrawn, theflights with the locked-in soil will be raised to levels some distance(typically up to 20 m) above the ground, and there is a significantdanger that the locked-in soil may loosen and fall onto operatingpersonnel on the ground, possibly causing serious injury. This isbecoming more of a problem with modern CFA piling techniques, sincethese often require a tight entry into the ground which results in soilbeing packed onto the flights in a particularly dense and compactmanner.

Traditionally, augers have been cleaned by hand, for example by using ascraping implement and sometimes water jets. This, however, is labourintensive and can be dangerous.

It is known from GB 2 235 480 A (amongst others) to scrape soil off theflights of a rotating auger by deploying a toothed wheel next to theauger in the manner of a worm drive. As the auger rotates, so does thewheel, the teeth of the wheel engaging between the flights and therebyscraping off locked-in soil. This technique is not particularlyeffective, since only soil locked in a single flight is attacked at anyone time. Furthermore, if the auger is being withdrawn rather thanmerely being rotated out of the ground, then the toothed wheel will tendto miss sections of the auger flights.

OBJECT AND SUMMARY OF THE INVENTION

According to the present invention, there is provided a tool forremoving debris from the flights of an auger or other screw-conveyor,the tool comprising a central shaft about which is helically arranged aplurality of radially projecting elements.

In use, the tool is mounted adjacent to an auger with the central shaftbeing substantially parallel to the auger stem. Advantageously, the toolis mounted in such a way that it can be moved near to and away from theauger in such a way that the projecting elements may be graduallyintroduced to the auger flights. Cleaning the auger in this manner isassisted by way of soil being packed more loosely between the flights atthe top of the auger than between those at the bottom. The radiallyprojecting elements are arranged in a helix wherein the elements areangularly and axially displaced from each other on a central axis, in amanner in which the helix has substantially the same pitch as that ofthe auger blade. As the auger is withdrawn from the ground, the tool isbrought up to the auger and rotated so that the projecting elementsengage with the auger flights. The rate and direction of rotation isdependent on the rate of withdrawal of the auger and whether or not theauger is also being rotated. In general, where the projecting elementsare disposed in a helix having the opposite sense to that of the augerblade, then the tool must be rotated in the opposite direction to theauger so as to counter flight movement. Alternatively, the projectingelements may be disposed in a helix having the same sense as that of theauger blade, in which case the tool is rotated in the same direction asthe auger. The former arrangement may be advantageous in that the angleof attack of the projecting elements on the flights of the auger isincreased, and any locked-in soil will tend to be pushed downwards.

It is also possible to clean the auger without continuous rotation uponextraction. The auger may, for example, be repeatedly turned forwards byhalf a turn and then backwards by half a turn, with the tool rotatingaccordingly.

A particular advantage of the present invention is that it can be usedin applications where an auger is rotated relatively slowly duringwithdrawal. This is because the projecting elements simultaneouslypenetrate adjacent flights of the auger. Furthermore, since rotation ofthe tool allows continuous parallel movement between the tool and theauger, the tool does not need to be separated from and repositioned onthe auger as it is withdrawn. This helps to ensure that no sectionsalong the length of the auger are missed. Advantageously, two, three ormore tools may be disposed substantially equiangularly about the augerso as to attack soil on the auger flights from a number of directionssimultaneously. Such an arrangement, particularly with three tools, alsomeans that any lateral forces which may tend to push a single tool andthe auger away from each other may be balanced out.

The tool may be rotated by way of a mechanical linkage which couples thetool to the auger drive means. Such a linkage, which may take the formof a bushing or other driving arrangement, automatically synchronisesthe rotations of the tool and the auger so as to prevent relativefouling.

Alternatively, the tool may be rotated by way of an independent electricor hydraulic motor. In order to ensure synchronisation with the rotationof the auger, sensors are provided which detect the proximity of theauger flights to the tool. When a sensor detects that the tool and theauger are not in synchronisation, i.e. the projecting elements are notdisposed substantially in the middle of each flight, appropriaterotation of the tool is commanded so as to bring the projecting elementsback to the mid-point of each flight. On-board instrumentation andcomputer means may be provided so as to allow complete control of thetool. For example, given the angle of rotation of the auger, the depthchange and the pitch of the auger blade, it is possible to calculate andapply the correct rate of rotation to the tool so as to ensuresynchronisation with the auger.

The radially projecting elements may take the form of blades, cuttingtools, digging tools, brushes and any combination thereof. It isgenerally preferred to include at least one blade or cutting tool, sincesoil removal is facilitated by cutting a groove into the locked-in soilso as to allow the same to swell and hence to fall away from the auger.The radial extension of at least some of the projecting elements shouldbe at least as great as the radius of the largest auger with which thetool is to be used. This is to ensure that the flights are cleanedthoroughly. In some embodiments, the envelope defining the radialextension of the projecting elements may be selected to start from thediameter of the central shaft at the lower end of the tool and graduallyto increase along the length of the tool until full penetration of theauger flights is achieved. A further feature is that differentprojecting elements may be arranged along the length of the tool so asto facilitate the removal of different conditions of soil, for exampleloosely- or densely-packed. For example, brushes can be arranged at thetop of the tool so as to complete the auger cleaning operation. Theprojecting elements need not be permanently attached to the centralshaft of the tool, but may be readily interchanged so as to allow thetool to be tailored to specific applications.

In embodiments where the tool is mounted so that it may be moved near toand away from the auger, generally by way of a pivot, it is possible toswing the tool out of the way of any drive head which may be mounted atthe top of the auger, thereby allowing the auger to be rotated into theground to a greater depth than would otherwise, be possible. One way inwhich this may be achieved is to drive the tool from its lower end.

BRIEF DESCRIPTION OF THE INVENTION

For a better understanding of the present invention, and to show how itmay be carried into effect, reference will now be made, by way ofexample, to the following drawings, in which:

FIG. 1 shows an auger cleaning tool engaged with an auger;

FIG. 2 shows a pivotally-mounted auger cleaning tool engaged with anauger; and

FIG. 3 shows the auger cleaning tool of FIG. 2 moved to a position awayfrom the auger.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows an auger 1 having a blade 2. A tool 3, comprising a centralshaft 4 on which are removably mounted a number of flat blades 5 in ahelical formation wherein the blades 5 are angularly and axiallydisplaced from each other on central axis 4 so that each blade 5,engages with the blade 2 of the auger 1. The pitch of the blades 5 issubstantially the same as the pitch of the auger blade 2, and the senseof the helical arrangement of the blades 5 is opposite to that of theblade 2. In the embodiment shown, the tool 3 has a length of around 1 to2 m, and the auger 1 has a length of up to 20 m. In use, as the auger 1is withdrawn from the ground, the tool 3 is rotated so as to counter themovement of the blade 2 of the auger 1. Rotation of the tool 3 issynchronised with rotation of the auger 1 so that the blades 5 penetrateadjacent flights 6, 6′ without fouling the blade 2 itself. In this way,any soil (not shown) locked into the flights 6, 6′ of the auger 1 iseffectively removed.

As shown in FIG. 1, the tool is rotated by drive means comprising anelectric on hydraulic motor 14. In order to ensure synchronization withthe rotation of the auger, sensors 15 are provided which detect theproximity of the auger flights to the tool. When a sensor 15 detectsthat the tool and the auger are not in synchronization, appropriaterotation of the tool is commanded by feedback control 16 to bring theprojecting elements back to the midpoint of each flight without foulingthe blade.

An alternative arrangement is shown in FIGS. 2 and 3, where an augercleaning tool 7 is pivotably mounted next to an auger 8. The auger 8 isrotated by way of a drive head 9 mounted at the top of the auger 8. Thedrive head also serves to rotate the tool 7 in the appropriate directionby way of a shaft 10 and mechanical linkages 11 and 12. As shown best inFIG. 3, the tool 7 may be swung away from the auger 8 so that it nolonger engages with the flights 13, 13′ of the auger, thereby allowingthe drive head 9 to pass by most of the body of the tool 7 and therebyenabling the auger to penetrate the ground to a deeper level than wouldotherwise be the case.

What is claimed is:
 1. A tool for removing debris from flights of ablade of an auger or other screw conveyor, the tool comprising a centralshaft about which is helically arranged a plurality of radiallyprojecting elements, wherein said projecting elements are disposed aboutsaid central shaft such that there exists an angular displacement and anaxial displacement between each of the projecting elements.
 2. A tool asclaimed in claim 1, wherein the radially projecting elements areselected from the group consisting of blades, cutting tools, and diggingtools.
 3. A tool as claimed in claim 1, wherein the radially projectingelements comprise brushes.
 4. A tool as claimed in claim 1, 2, whereinthe radially projecting elements are detachably mounted on the centralshaft.
 5. A tool as claimed in claim 1, wherein the radial extension ofthe radially projecting elements increases along at least a portion ofthe length of the tool from bottom to top.
 6. A tool as claimed in claim1, wherein the tool, in use, is rotatably mounted adjacent the augersuch that at least some of the radially projecting elements penetrate atleast some of the flights of the auger.
 7. A tool as claimed in claim 6,wherein the tool, in use, is mounted so that it may be moved near to andaway from the auger in such a way that the radially projecting elementsmay be gradually introduced into the flights of the auger.
 8. A tool asclaimed in claim 7, wherein the tool may be moved away from the auger soas to allow the auger to bypass at least part of the tool duringinsertion and extraction.
 9. A tool as claimed in claim 6, wherein thetool is mechanically coupled to drive means adapted to rotate the auger,such that the tool is rotated in synchronism with the auger.
 10. A toolas claimed in claim 6, wherein the tool is provided with separaterotational drive means and with sensors which detect the proximity ofthe radially projecting elements to the blade of the auger, a feedbackcontrol mechanism being provided between the drive means and the sensorswhich controls the rotation of the tool so as to tend to pass theprojecting elements between adjacent flights without fouling the blade.